JPH0836780A - Integrated optical unit - Google Patents

Abstract

PURPOSE:To accurately position components and to reduce the size and thickness of an integrated optical unit by fixing a semiconductor laser, a signal detecting photodetector to the vertical wall of a mounting board, and fixing reciprocating isolation elements to the two protruding corners of the wall. CONSTITUTION:A mounting board 600 is removed except protrusions 601-605 by anisotropic etching. The left end vertical wall of the protrusion 601 is coated, a semiconductor layer 101 is positioned there, and the position is adjusted, and connected to it. The corners of the protrusions 602, 603 are used as positioning guides, a multi-image parallel flat plate 301 is inhibited to be rotated, and adhered. Further, on the right end vertical walls of the protrusions 604, 605, a signal detecting photodetector 306 is mounted as to be x-y-adjustable. A light quantity monitoring photodetector 305 is positioned at the upper end vertical walls of the protrusions 603, 604 by roughly regulating and adhered. Thus, the optical conjugate distance relationship among the laser 101, the plate 301 and the detector 306 is easily held and the distance relationship in the optical axial directions can be precisely obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an integrated optical unit used in an optical recording medium, particularly an optical recording medium device for recording / reproducing information on / from a magneto-optical recording medium.

[0002]

2. Description of the Related Art As a conventional optical head, for example, FIG.
The one shown in 1 is proposed. This optical head records / reproduces information on / from a magneto-optical recording medium. A linearly polarized divergent light beam from a semiconductor laser 101 is made incident on a polarizing beam splitter 102, and a polarizing film formed on a joint surface thereof. The light flux reflected by 103 passes through the objective lens 104 and the information track 10 of the magneto-optical recording medium 105.
Irradiation on 6 as a minute spot. The polarizing film 103 of the polarization beam splitter 102 has a characteristic that a vibration component (s-polarized light) in a direction perpendicular to the paper surface is reflected by 60 to 90%, and a vibration component (p-polarized light = signal component) in the paper surface is transmitted by almost 100%. As described above, the linearly polarized light from the semiconductor laser 101 is s-polarized and is formed by the dielectric multilayer film.
It is designed to enter 3.

The return light reflected by the magneto-optical recording medium 105 and having its polarization plane rotated ± θk around the optical axis according to the recorded information is incident on the polarization beam splitter 102 again as a convergent beam through the objective lens 104. , The polarizing film 10
After passing through 3, the light is spatially separated from the forward path and enters the multi-image prism 107. Multi-image prism 1
07 is configured by joining a first triangular prism 108 and a second triangular prism 109 each made of a birefringent crystal, and the optical axis of the first triangular prism 108 on which the return light first enters is the magneto-optical In order to detect a signal (hereinafter referred to as MO signal) by a differential method, the signal is set to be perpendicular to the optical axis of the returning light and inclined by 45 ° in the direction perpendicular to the paper surface,
The optical axis of the second triangular prism 109 is set to be inclined, for example, by 45 ° in the direction perpendicular to the optical axis with respect to the optical axis of the first triangular prism 108. Therefore, the return light that has entered the multi-image prism 107 is substantially split into three light beams and emitted from the multi-image prism 107.

The three beams emitted from the multi-image prism 107 pass through a toric lens 110 and a photodetector 11
Incident on 1. The toric lens 110 has a concave lens function of extending the focal length of transmitted light and a cylindrical lens function of generating astigmatism for detecting a focus error signal (hereinafter referred to as FES). In addition, the photodetector 11
As shown in FIG. 12, reference numeral 1 has three light receiving portions 112, 113 and 114 for separating and receiving three light fluxes having astigmatism, and the central light receiving portion 114 is a four-divided light receiving area. The MO signal is detected based on the difference between the outputs of the light receiving units 112 and 113, and the FES is detected based on the difference between the outputs of the diagonal light receiving regions of the light receiving unit 114. Although not shown, the tracking error signal (hereinafter referred to as TES) can be detected by, for example, a push-pull (hereinafter referred to as PP) method.

[0005]

However, in the conventional optical head, a housing for accommodating and fixing each optical component is molded by machining using a lathe, a milling machine, an NC machine or the like, and is screwed to the housing. The optical parts are fixed by adhesion or adhesion. Therefore, the housing becomes large and complicated, and it becomes difficult to position and mount the optical component on the order of μm.

In particular, when the number of parts is large as in the above-mentioned optical head, the mounting dimension of the part shown by the chain double-dashed line in FIG. 11 is several tens to several in order to secure the space occupied by the parts and its adjusting mechanism. It becomes as large as about 100 mm. For this reason, when mounting, an expensive housing divided into several blocks that require complicated processing is required, and at the same time, the processing error of each optical component and each housing is accumulated, and the error is absorbed. Therefore, for example, the xyz-axis adjustment of the photodetector 111, or the photodetector 111
It is indispensable to make adjustments in the three axial directions such as the xy axis adjustment and the toric lens 110 z axis adjustment. Moreover, this xy
Since the axis adjustment and the z-axis adjustment are not independent of each other and interfere with each other, repeated adjustments are required, resulting in a great increase in the number of steps.

Further, since the light emitting surface of the semiconductor laser 101 and the light receiving surface of the photodetector 111, which are in an optically conjugate positional relationship with each other, are spatially widely separated from each other, they are vulnerable to temperature changes and aging changes. There is a problem that it is difficult to maintain the environment resistance characteristics.

The present invention has been made by paying attention to the above-mentioned conventional problems, and it is possible to secure the processing accuracy of the mounting substrate, to accurately position and mount the optical component, and
It is an object of the present invention to provide an integrated optical unit that is small in size, thin, inexpensive, and excellent in environmental resistance.

[0009]

In order to achieve the above object, the present invention is an integrated optical unit used in an optical recording medium device for recording / reproducing information on / from an optical recording medium. Is a (110) silicon wafer and has a plurality of vertical walls having {111} as its side surfaces, and a semiconductor laser fixed to the (111) vertical walls of this mounting substrate is different from (111). A photodetector fixed to the vertical wall and receiving return light from the optical recording medium and a photodetector fixed to at least two convex corners of the different (111) vertical wall are fixed to prevent rotation of the light flux from the semiconductor laser. It is characterized in that it has a round-trip path separating element which guides the return light from the optical recording medium to the photodetector side while guiding it to the optical recording medium side.

The vertical wall to which the semiconductor laser is fixed and the vertical wall to which the photodetector is fixed have the same azimuth (1
The 11) plane is the distance relationship in the optical axis direction between the semiconductor laser, the photodetector, and the round-trip path separating element in μm.
It is preferable because it can be secured on the order.

The mounting substrate has through air holes for adsorbing at least one of the semiconductor laser and the photodetector to the corresponding vertical wall. It is preferable in that it is fixed to the corresponding vertical wall.

[0012]

In the present invention, since the mounting substrate is made of (110) silicon wafer processed so that at least the uppermost surface becomes a vertical wall having {111} as its side surface,
It is possible to obtain a plurality of vertical walls for fixing the semiconductor laser, the photodetector and the reciprocal path separating element on one mounting substrate with high precision on the order of μm by the optical reduction method and anisotropic etching. . Therefore, it is possible to accurately position and mount optical components, and to obtain an integrated optical unit that is small in size, thin, inexpensive, and excellent in environmental resistance with good mass productivity.

[0013]

FIG. 1 shows the basic structure of an optical system of an optical recording medium device in which an integrated optical unit according to the present invention is used. A portion surrounded by a chain double-dashed line is a non-common optical path of a reciprocating path. 1 shows an integrated optical unit having a semiconductor laser 101 forming a laser beam, a photodetector 111 for signal detection, and a round-trip path separation element 201. In the outward path, which is the imaging optical path,
The light beam emitted from the semiconductor laser 101 is reflected by the round-trip path separation element 201, and then imaged as a minute spot on the magneto-optical recording medium 105 by the objective lens 104.

In the return path, which is the signal detection optical path, the return light reflected by the magneto-optical recording medium 105 is the objective lens 1.
After passing through 04, the light enters the reciprocal path separation element 201 again, and the transmitted light is spatially separated from the forward path, and the photodetector 111
To the FE, and based on the output of this photodetector 111,
S, TES, MO signals are detected.

Here, the round-trip path separating element 201 is a semi-transparent plate or a semi-transparent prism that uses transmission and reflection, a grating that uses 0th order light on the forward path and high-order diffracted light on the return path,
It can be configured by a polarization beam splitter or the like which also constitutes an optical isolator in common with the quarter-wave plate.

In FIG. 1, the distance from the semiconductor laser 101 to the round trip path separating element 201 is a, and the round trip path separating element 2 is
If the distance from 01 to the photodetector 111 is b, then a =
When b is through the round trip path separating element 201, the semiconductor laser 101 and the photodetector 111 have a positional relationship of optical conjugate points. Therefore, if the semiconductor laser 101, the photodetector 111, and the reciprocal path separation element 201 are integrated as an integrated optical unit and their positional relationship is reliably positioned and compactly mounted, even if disturbance occurs in the common optical path. , Optical performance will not be disturbed.

The semiconductor laser 101 and the photodetector 11
The positional relationship with 1 can be replaced if the reciprocal path separation element 201 is transmitted on the outward path and reflected on the return path, and if a reflecting member is provided behind the reciprocal path separation element 201 on the return path, both can be replaced. It is also possible to arrange them in the same direction.

FIG. 2 shows an example of the configuration of an optical system of an optical recording medium device when the integrated optical unit according to the present invention is used. This optical system is for a magneto-optical recording medium and is an infinite system. A linearly polarized divergent light beam from the semiconductor laser 101 is incident on a multi-image parallel plane plate 301 having a polarization film 304, and the light beam transmitted through the polarization film 304 and the multi-image parallel plane plate 301 is detected by a photodetector 305 for light amount monitoring. Is received by the collimator lens 3 and the amount of light emitted from the semiconductor laser 101 is controlled based on the output of the collimator lens 3.
A parallel light flux is formed at 10 and is irradiated as a minute spot on the information track 106 of the magneto-optical recording medium 105 by the objective lens 104.

The return light reflected by the magneto-optical recording medium 105 is the objective lens 104 and the collimator lens 3.
By making the light incident on the polarizing film 304 via 10, the return light passing through the polarizing film 304 is spatially separated from the outward light and made incident on the multi-image plane parallel plate 301. The return light that has entered the multi-image parallel plane plate 301 is refracted and transmitted through the multi-image parallel plane plate 301 to impart astigmatism and polarization-separated, and the polarization-separated light flux is used as a signal detection photodetector. Thirty
Light is received at 6, and the MO signal, FES, and TES are detected.

The semiconductor laser 101 is arranged so that the direction of the linearly polarized light of its emitted light enters the polarizing film 304 as s-polarized light. The multi-image plane parallel plate 301 is configured by bonding a first triangular prism 302 and a second triangular prism 303 each made of a birefringent crystal, for example, lithium niobate, and divergent light flux from the semiconductor laser 101 and magneto-optical property. A polarizing film 304 is formed on the surface of the first triangular prism 302 on which the return light from the recording medium 105 is incident. The polarization film 304, for example, has a characteristic that a vibration component (s-polarized light) in a direction orthogonal to the paper surface is reflected by 60 to 90%, and a vibration component in the paper surface (p-polarized light = signal component) is transmitted almost 100% in terms of signal detection efficiency. And a dielectric multi-layer film.

The optical axis of the first triangular prism 302 is perpendicular to the optical axis of the incident light linearly polarized in the y direction and in the direction perpendicular to the paper surface in order to detect the MO signal by the differential method. The optical axis of the second triangular prism 303 is set such that the return light is divided into two equal oscillation components of the ordinary light and the extraordinary light, which are orthogonal to each other, and the optical axis of the second triangular prism 303 is the optical axis of the first triangular prism 302. On the other hand, in the plane perpendicular to the optical axis, that is, the optical axis is inclined by a predetermined angle.

When the optical axes of the first and second triangular prisms 302 and 303 are set in this manner, the linearly polarized light of the incident light (return light) is converted by the first triangular prism 302 into the ordinary light O of substantially equal intensity. And extraordinary light E is polarized and separated, and further by the second triangular prism 303,
Each ray is polarized and separated into ordinary rays OO and EO and extraordinary rays OE and EE to be a total of four luminous fluxes. Here, the light fluxes OO and EE almost overlap, and the light fluxes OE and EO
Are refracted and transmitted in directions opposite to each other, so that substantially three light beams are separated and emitted from the multi-image plane parallel plate 301.

The signal detecting photodetector 306 which receives the return light emitted from the multi-image plane parallel plate 301 has its light-receiving surface at the best image plane position of astigmatism due to the multi-image plane parallel plate 301, that is, multi-image. The parallel plane plate 301 is arranged so as to be located approximately in the middle between the focal plane in the x direction and the focal plane in the y direction. As shown in the plan view of FIG. 3, the detector 306 has a light receiving region 307 that receives the light beam EO from the multi-image plane parallel plate 301 and a light receiving region 308 that receives the light beam OE.
And a four-division light receiving area 30 for receiving the light beams OO and EE
9 and are provided.

According to this optical system, the MO signal can be detected based on the difference between the outputs of the light receiving regions 307 and 308 which separate and receive the polarization components orthogonal to each other in the same manner as the configuration in FIG. At the same time, the FES can be detected based on the difference in the diagonal sum outputs of the four-divided light receiving regions 309 that receive almost equal amounts of orthogonal polarization components.
Further, TES can be detected by the PP method based on the output of the four-division light receiving area 309. The intensity ratio of the light beams (EO), (OE) and (OO + EE) incident on the light receiving regions 307 and 308 and the four-division light receiving region 309 is determined by the angle formed by the optical axes of the first and second triangular prisms 202 and 203. Can be arbitrarily set by appropriately selecting, for example, if this is set to 90 ° and a so-called Wollaston prism is formed, the intensity of (OO + EE) becomes zero.

In constructing the optical system shown in FIG.
In order to realize a compact and thin optical head, the distance from the multi-image plane parallel plate 301 to the signal detection photodetector 306 is
It is desired to suppress the thickness to about 1 to 2 mm.

As a practical design value, when the beam shaping function is not provided, the NA of the collimator lens 310 (objective lens 104 in the finite system) on the semiconductor laser side is 0.15, and the recording medium of the objective lens 104. NA on the side is 0.
It is considered to be about 3.7 times that of 55. In the case of having a beam shaping function, the NA of the collimator lens 310
Becomes smaller, the magnification becomes higher.

In this case, the depth of focus on the surface of the recording medium is ± 1.
Since the recording medium is a reflection system, the movement of the image in the corresponding optical axis direction on the signal detecting photodetector 306 is ± 1 μm × 2 × 3.7 ² ≈ ± 27 μm. Within this range, it is difficult to adjust the signal detection photodetector 306 in the three axis directions. Therefore, conventionally, by using a concave lens to increase the magnification, it is possible to increase the positioning accuracy and adjust the optical axis direction. However, in order to realize a compact and thin optical head, such a concave lens is used. Is not preferable.

If the signal detecting photodetector 306 is to be adjusted in the biaxial directions of the xy plane, the signal detecting photodetector 306 in the optical axis direction with respect to the virtual conjugate position of the light emitting point of the semiconductor laser 101. Positioning accuracy is required.
Moreover, in this case, other errors in the optical axis direction cannot be absorbed by the adjustment, so that the positioning accuracy of the semiconductor laser 101 in the optical axis direction and the multi-image plane parallel plate 30 can be improved.
The thickness error of No. 1, the positioning accuracy of the multi-image plane parallel plate 301, the positioning accuracy of the photodetector 306 for signal detection, and other errors must be suppressed to ± 10 μm or less in consideration of variations in the normal distribution.

In the optical system shown in FIG. 2, the distance from the semiconductor laser 101 to the polarizing film 304 is a, and the polarizing film 30 is
4, the distance from the multi-image parallel plane plate 301 to the signal detection photodetector 306 is b + c, and the refractive index of the multi-image parallel plane plate 301 is n, the semiconductor laser 101 and the multi-image parallel plane plate 301 are interposed. The positional relationship of the optical conjugate point with the signal detecting photodetector 306 is a = b / n + c.

Here, as a practical numerical value in consideration of miniaturization and thinning, a = 2.5 mm, multi-image plane parallel plate 30
When the thickness t of 1 is t = 2 mm and n = 2.2, the photodetector 306 for signal detection is output from the exit point of the multi-image plane parallel plate 301.
Distance c is about 1.5 mm, and it becomes difficult to mount it on a normally machined housing with the required accuracy. In addition, when performing 3-axis adjustment within this space, the adjustment man-hour Will be increased.

In the embodiment of the present invention, a silicon wafer whose uppermost surface is (110) is anisotropically etched to form a plurality of vertical walls having {111} as side surfaces, which is used as a mounting substrate. The semiconductor laser 101 and the multi-image parallel plane plate 301 are fixed to different vertical walls of the mounting substrate, and the signal detection photodetector 306 is stopped from rotating at least two convex corners of the vertical wall. They are fixed to form an integrated optical unit.

Hereinafter, referring to FIGS. 4 and 5, (11
The basic items and the design items to be noted when applying the anisotropic etching of the deep groove to the silicon wafer of 0) will be described. Anisotropic etching in the case of using single crystal silicon as the material to be processed utilizes that the etching rate has a large crystal orientation dependency with respect to an etchant KOH (potassium hydroxide) aqueous solution or the like. The etching rate of the crystal plane (111) of silicon is extremely smaller than that of other crystal planes, and the crystal plane (110) shows the maximum value.
The ratio of the two etch rates reaches 1: 180.
Utilizing this characteristic, as shown in FIG.
0) <1-12> or <-112> on the wafer surface
4 (in the text, the bar above the numeral shown in FIG. 4 is described before the numeral for convenience. Hereinafter, it is described as follows.) When a mask opening is provided and etching is performed, the angle formed is 109. The {111} side walls of 5 ° and 70.5 ° appear on four sides, the side etching is small, and a deep groove cut directly below the opening can be obtained. Moreover, if the ratio of both etch rates is about 1: 180, for example, 1.2 mm
Even in the case of ultra-deep groove machining, the error from the vertical line between the upper and lower surfaces can be suppressed within 7 μm.

Here, (110) silicon is replaced by {11
The first design item to be noted when performing anisotropic processing using 1} as a sidewall is that a (111) plane that is not parallel to the top surface appears on the etching bottom surface. This state is shown in FIG.
The description will be made with reference to the z-axis cross-sectional view seen from the arrow b direction of FIG. 4A shown in FIG. FIG. 4B shows that when a (110) wafer is used, it forms an angle of 35.3 ° with the upper surface in addition to the four (111) side surfaces perpendicular to the upper surface (111).
It shows that two surfaces appear. These faces are 7
It appears from the corners on both sides of 0.5 °, and the area that appears appears as the etching in the depth direction progresses, and finally reaches the depth at which the bilateral (111) planes of the bottom surface collide, that is, other than the {111} plane. The surface progresses to a depth where etching is completed.

This state is shown in FIGS. 5 (a) and 5 (b). FIG. 5 (a) shows a process in progress of etching. This etching is substantially automatically stopped in the state shown in FIG. 5 (b), and all four sidewalls and two slopes (11
1) It becomes a surface. Therefore, the corner of 70.5 ° is set as an extra mask dimension in consideration of the groove depth and the flat portion of the bottom surface to be secured. Assuming that the required groove depth is d, the assured flat etching bottom surface is located at a distance of 35.3 ° from the corner of 70.5 ° in the bisector direction.

The second design item to be noted is that, as a result of etching, higher-order surfaces appear on the convex corners, the convex corners are rounded, and dimensional accuracy cannot be ensured.
To prevent this, for example, the shape of the mask is slightly corrected in advance. In this regard, for example, B. Puers,
and W. Sansen, "Compensation Structures for Convex
Corner Micromachining in Silicon ", Sensors and Act
uators, A21-A23, 1990, pp.1036-1941.

Embodiments of the integrated optical unit of the present invention will be described below on the premise of the magneto-optical system shown in FIG. 2. However, each embodiment described below is a semiconductor laser, a round-trip path separating element. Needless to say, the present invention can be applied to all optical systems for optical recording media having a photodetector for signal detection, for example, a CD that does not require a polarization separation function.
In the case of a (compact disk) head, the reciprocating path separation element may be replaced with, for example, a simple parallel plate.

FIG. 6 is a plan view showing the first embodiment of the present invention. The mounting substrate 600 is made of a silicon wafer having a top surface of (110), and is removed by anisotropic etching to a depth of 1.2 mm except for the convex portions 601 to 605 shown by hatching. In FIG.
On the silicon wafer where the convex part is directly dicer cut
Except for the lower and left side surfaces, the side wall surfaces having a depth of 1.2 mm are all vertical walls of the (111) plane formed by etching, and the right surface has the (111) vertical wall up to a depth of 1.2 mm.
The remaining thickness, for example, 0.5 mm is dicer cut.

A coating process for joining the semiconductor laser is applied to the left end vertical wall of the convex portion 601, and the semiconductor laser 101 is positioned and adjusted by the junction down in consideration of the heat radiation effect on the vertical wall. To join. Also,
The convex portions 602 and 603 use the respective corners of 109.5 ° as positioning guides to position and bond the multi-image plane parallel plate 301 while the rotation is stopped. Since the multi-image plane parallel plate 301 has a large tolerance for rotation with respect to the optical conjugate distance in the optical axis direction between the semiconductor laser 101 and the signal detection photodetector 306, the projections 602 and 603 have a large tolerance. The error in the dimensional accuracy of a convex corner is
Does not affect much.

The convex portions 604 and 605 are formed such that their right end vertical walls are located in the same plane, and the signal detecting photodetector 306 is attached to the right end vertical walls of these convex portions 604 and 605 by x, y Position and mount in an adjustable state. Further, since the upper end vertical walls of the convex portions 603 and 604 are dicer cut surfaces and are in the same plane, the light amount monitor photodetector 305 is positioned and adhered to these surfaces by rough adjustment. Note that the photodetector 306 for signal detection
Further, wiring light submounts 607 and 606 are integrally attached to the light amount monitor photodetector 305.

The height of each optical component is, for example, about 1 mm, the optical axis (center of the light beam) is set near the middle between the bottom surface and the upper surface, and the optical path through which the light beam passes naturally has a convex portion. Avoid and design. In this embodiment, the corner of 70.5 ° is not used for the groove portion to be etched so that the flat portion of the etching bottom surface can be secured even in the ultra deep groove processing. Further, even if the oblique (111) surface appears due to the influence of a plurality of adjacent patterns formed on the silicon wafer, the etching bottom surface of the region where the optical component is mounted is considered to be flat.

According to this embodiment, the semiconductor laser 101
And the signal-detecting photodetector 306 to (11
1) is fixed to the vertical wall of the plane, and the multi-image parallel plane plate 301 is fixed to the two convex corners of the vertical wall by stopping rotation, so that the semiconductor laser 101 and the multi-image plane parallel plate 3 are fixed.
01 and the signal detection photodetector 306 can easily maintain the optical conjugate distance relationship between them, and the distance relationship in the optical axis direction can be secured on the order of μm.

In the first embodiment, the signal detection photodetector 306 is premised on the xy adjustment. However, if the dimensional accuracy in the xy direction of each mounting part can be secured on the order of μm, the xy adjustment is performed. Becomes unnecessary. Also, xy
If accuracy is secured in at least one of the directions, for example, in the y direction, adjustment in the x direction is sufficient, and the effect becomes large.

For the xy adjustment of the mounted components, for example, in the case of an infinite optical system, even a collimator lens is integrated with an integrated optical unit to form a corner cube prism and a cat's eye consisting of a lens and a mirror placed at its focal position. It can be adjusted using an optical system such as an optical system that returns collimated light to the light source side as it is.

According to this embodiment, 3.5 mm × 7 mm
× All the parts shown in FIG. 6 can be mounted on the mounting substrate 600 having a thickness of about 1.7 mm. It should be noted that this embodiment is not limited to the optical head used in the magneto-optical recording medium device, but can be effectively applied to at least an optical head mounting a semiconductor laser, a photodetector, and a round-trip path separating element, and is similarly small in size. Can be realized.

FIG. 7 is a partial perspective view of the second embodiment of the present invention. In this embodiment, the mounting substrate 600 is placed on a (100) silicon wafer 702 having a thickness of about 0.5 mm.
For example, the (110) silicon wafer 701 is directly bonded or anodically bonded via an etching stopper layer 703 made of SiO ₂ , and the (110) silicon wafer 701 is anisotropy similarly to the first embodiment. By forming the convex portions 601 to 605 by etching, the semiconductor laser 10
1, multi-image plane parallel plate 301, photodetector 306 for signal detection
And a light quantity monitor photodetector 305 mounted,
Other configurations are the same as in the first embodiment.

In this way, the etching stopper layer 703 is formed.
By providing the above, since it is possible to easily secure the surface accuracy and the depth accuracy of the etching bottom surface, it is possible to easily perform the etching process.

In the third embodiment of the present invention, a virtual line is shown in FIG. 7 in order to facilitate the x, y adjustment of the photodetector 306 for signal detection on the order of μm and prevent the deviation at the time of bonding and fixing. As described above, the suction air holes 704 and 705 are formed by opening the right end vertical walls of the convex portions 604 and 605 to which the signal detection photodetector 306 is fixed. The suction air holes 704 and 705 are shown in FIG.
Are formed so as to penetrate the bottom surface of the mounting substrate 600, respectively, as shown by the AA cross-section position in FIG.

In forming the suction air holes 704 and 705, first, the suction air holes 704 and 704 are previously etched on the back surface of the (110) silicon wafer 701.
705 is formed. The length and width of the mask opening in this case are such that the etching is performed at a depth of about 0.8 to 1 mm in the sectional direction of the right end vertical wall surface of the projected portions 604 and 605 due to the action of the inclined (111) surface. Select to stop automatically. Further, an etching stopper layer 703 is formed on the (100) silicon wafer 702, and
00) Etching stopper layer 7 on silicon wafer 702
Through 03, through holes 801 corresponding to the suction air holes 704 and 705 are formed in advance by anisotropic etching.

Next, the (110) silicon wafer 701 and the (100) silicon wafer 702 are positioned and bonded, and then the (110) silicon wafer 70 is formed in the same manner as in the second embodiment.
1 is anisotropically etched to form projections 601 to 605. In this case, since the adsorption air holes that have already been formed are all (111) planes, even if the adsorption air holes are exposed to etching again, the hole shape is maintained.

9A and 9B show a state of anisotropic etching of the (100) silicon wafer 702. In the case of the (100) silicon wafer 702, unlike the case of the (110) silicon wafer 701, a rectangular pyramidal groove having a rectangular opening is formed by anisotropic etching, and the angle formed with the upper surface thereof is 54.7 °. . Figure 9
(A) shows a process in progress of etching, and four (1)
In addition to the (11) plane, the (100) plane still remains on the bottom surface. This etching stops when the etching progresses to the state shown in FIG. 9B, and only four (111) planes remain. Therefore, when the short side of the rectangle is 2 l, (1
00) The thickness of the silicon wafer 702 is set to l × tan54.7 °
With the following, the pyramidal groove can be penetrated.

In this way, the (110) silicon wafer 701 and the (100) silicon wafer 702 which have been preliminarily processed.
By joining and, it is possible to form suction air holes 704 and 705 penetrating from the right end vertical wall surfaces of the convex portions 604 and 605 to the bottom surface of the mounting substrate 600. Therefore, when the signal detection photodetector 306 is mounted, air is sucked from the bottom surface of the mounting substrate 600 through the suction air holes 704 and 705, so that the signal detection photodetector 306 is projected to the convex portions 604 and 605. Since the photodetector 306 for signal detection can be easily adjusted in x and y on the order of μm because it can be adsorbed to the right end vertical wall surface, it is possible to effectively prevent the deviation when adhering and fixing after the adjustment. it can. In addition, such an adsorption air hole, other optical parts,
For example, the semiconductor laser 101 and the light quantity monitor photodetector 3
It is also effective for 05.

FIG. 10 shows a fourth embodiment of the present invention. In this example, a convex portion 608 is further formed on the mounting substrate 600 by etching, and the convex portion 608 is formed.
The 70.5 ° corner is used as a positioning guide in the optical axis direction of the semiconductor laser 101, and other configurations are the same as those in the above-described embodiments. Here, the semiconductor laser 101 has the junction 6 down and the convex portion 6
The semiconductor laser 101 has a thickness of about 100 μm, and its light emitting surface is at a position of several μm from the surface bonded to the convex portion 601. Therefore, if the convex portion 608 is formed so that the corner of the convex portion 608 is located farther from the vicinity of the middle of the light emitting end face of the semiconductor laser 101, the corner serves as a positioning guide that presses the semiconductor laser 101 and positions it. Can be used.

The convex portion 608 is preferably formed outside the optical axis by 25 ° to 30 ° so as to prevent the light beam from the semiconductor laser 101 from being diffracted in the vicinity of the near field, and is also positioned for positioning 70. Accurately form a corner of 0.5 °.

According to this embodiment, the semiconductor laser 101
Is the left end vertical wall of the protrusion 601 and 70.5 of the protrusion 608.
Since it is mounted as a positioning guide with the corner of °,
There is an advantage that only a rough height direction (y direction) needs to be adjusted.

To summarize the effects of the embodiments described above,
It is as follows. Since parts that require precision and environmental resistance can be mounted in a single housing (mounting substrate 600) in a compact and accurate manner, it is easy to achieve high stability, low cost, and small size and light weight. Since the positional relationship in the optical axis direction of the semiconductor laser 101, the round-trip path separating element 301, and the signal detecting photodetector 306 is secured in the order of μm, the adjustment can be significantly simplified as compared with the conventional case. Further, in the case of an infinite system, adjustment can be performed using a simple pseudo optical system. That is, since the adjustments in the xy direction and the z direction do not interfere with each other, the adjustment with the intermediate characteristic value becomes possible. Since the adjustment location is only the signal detection photodetector 306, or this and the semiconductor laser 101, the number of adjustment steps can be significantly simplified. By further increasing the accuracy, it is possible to implement without any adjustment. The semiconductor laser 101 and the reciprocating path separation element 30 are mounted on a mounting substrate 600 of about 3.5 mm × 7 mm × 1.7 mm.
1. The signal detection photodetector 306, and even the light amount monitor photodetector 305 can be packaged. Therefore, in this state, by sealing everything with an inert gas, it becomes possible to dramatically extend the life of the device. Since the inclined (111) surface does not appear on the etching bottom surface and the convex 70.5 ° corner is used only for positioning the semiconductor laser 101 in the optical axis direction, it is easy to ensure accuracy. . Semiconductor laser 101 and photodetector 30 for signal detection
The vertical wall to which 6 is fixed is a (111) plane in the same direction, and since the multi-image parallel plane plate 301 is fixed by stopping rotation so that there is no displacement, the multi-image parallel plane plate 301 is fixed in the optical axis direction between these three. The distance relationship can be secured on the order of μm.

[0056]

According to the present invention, a mounting substrate having a plurality of vertical walls formed with {111} as the side faces is used on at least the uppermost surface of a (110) silicon wafer, and the vertical walls of the mounting substrate are used. Since the semiconductor laser and the photodetector for signal detection are fixed and the round-trip path separating element is fixed to at least two convex corners of the vertical wall by rotation, the optical components are accurately positioned and mounted. In addition, it is possible to obtain an integrated optical unit that is small, thin, inexpensive, and excellent in environment resistance.

[Brief description of drawings]

FIG. 1 is a diagram showing a basic configuration of an optical system of an optical recording medium device when an integrated optical unit according to the present invention is used.

FIG. 2 is a diagram showing a configuration of an example of an optical system of an optical recording medium device when the integrated optical unit according to the present invention is used.

FIG. 3 is a diagram showing a configuration of a photodetector for signal detection shown in FIG.

FIG. 4 is a diagram for explaining anisotropic etching of a (110) silicon wafer.

FIG. 5 is also a drawing for explaining anisotropic etching of a (110) silicon wafer.

FIG. 6 is a diagram showing a first embodiment of the present invention.

FIG. 7 is also a diagram showing a second embodiment.

FIG. 8 is likewise a diagram showing a third embodiment.

FIG. 9 is a diagram for explaining anisotropic etching of a (100) silicon wafer in a third example.

FIG. 10 is a diagram showing a fourth embodiment of the present invention.

FIG. 11 is a diagram showing a conventional optical head.

12 is a diagram showing a configuration of the signal detection photodetector shown in FIG.

[Explanation of symbols]

 Reference Signs List 101 semiconductor laser 103 polarizing film 104 objective lens 105 magneto-optical recording medium 106 information track 111 photodetector 201 reciprocating path separation element 301 multi-image parallel plane plate 305 light intensity monitor photodetector 310 collimator lens 306 signal detection photodetector 600 Mounting substrate 601 to 605, 608 Convex portion 701 (110) Silicon wafer 702 (100) Silicon wafer 703 Etching stopper layer 704, 705 Adsorption air hole

Claims (3)

[Claims] 1. An integrated optical unit used in an optical recording medium device for recording / reproducing information on / from an optical recording medium, wherein at least an uppermost surface is made of a (110) silicon wafer, and {111} is a side surface. A mounting substrate having a plurality of vertical walls, a semiconductor laser fixed to a (111) vertical wall of the mounting substrate, and a return light from the optical recording medium fixed to a different (111) vertical wall. A photodetector for receiving light and at least two convex corners of different (111) vertical walls are fixed to prevent rotation, and guide the light beam from the semiconductor laser to the optical recording medium side, and An integrated optical unit, comprising: a round-trip path separating element that guides return light to the photodetector side. 2. The integrated optical unit according to claim 1, wherein the vertical wall to which the semiconductor laser is fixed and the vertical wall to which the photodetector is fixed are (111) planes having the same orientation. . 3. The mounting substrate according to claim 1, wherein the mounting substrate has a through air hole for adsorbing at least one of the semiconductor laser and the photodetector to a corresponding vertical wall. Integrated optical unit.